Unauthorised account deduction

Monday 16 October 2017 I was transferred money by someone who owed me then yesterday the person went to a branch and claimed they sent it to the wrong person and wants the money back. Instead of the consultant following process and logging a service request,she just went into my cheque account and withdrew the money from my account,no call, no authorisation and no security check all she had was the person's word. So I spent hours inside a branch demanding answers because I fail to understand how is this even legal let alone a process that Standard Bank now follows?! I am not happy at all because now my money is gone and my account is in a negative balance because of this and I want my money back,not after an ongoing investigation but now as I am not accepting any of this nonsense service from the bank!! This is really bad service and to top it all off a violation of my rights and security of my bank account!!!